Method and system for evaluating casing deformation resistance of cement stone for well cementation of oil and gas well

The invention provides a method and a system for evaluating the casing deformation resistance of cement stone for well cementation of an oil and gas well, and the method specifically comprises the following steps: preparing cement slurry for well cementation, and filling a mold annulus with the prepared cement slurry to obtain a sample; applying a non-uniform external extrusion or shear load to the sample by adopting a shear test device so as to simulate the stratum displacement; the relative displacement delta S and the radial size variation delta D of the inner cylinder of the mold are determined; based on the relative displacement delta S and the radial size variation delta D, determining the deformation delta L of the sample; and judging whether the deformation delta L of the sample is greater than 25mm or not, if so, considering that the cement paste belongs to large-strain cement paste and the formed cement stone has the capability of inhibiting the deformation of the casing, and otherwise, considering